What does he mean "virtually no impact?" Ron Hughes, chief engineer for the Jesse Brown VA Medical Center (VAMC) in Chicago is n ot speaking negatively when he describes how reliably the new cogeneration system fit into hospital operations.

The 3.4-MW cogeneration (combined heat and power) system is the major element of the new energy center, designed and built by the comprehensive energy services firm, Energy Systems Group (ESG). It seamlessly took over supplying power to the medical center from the local utility, Commonwealth Edison (ComEd), without a blip, and it has been operating in the 98% availability range since it began commercial operations in February 2004, according to Luke Brockman, vice president of ESG’s energy service group, which runs the energy center.

While actual annual savings won’t be known for another few months, based on the estimated savings of $31 million over 25 years, the $13 million investment should be paid back in about 10 years. However, the VA isn’t worried about the numbers, since it had no up-front investment costs. Its first concern was reliability and independence.

VA Sought Independence
The project was initiated when hospital management decided energy independence would provide greater security and reliability for the Jesse Brown VAMC. It is a 209-bed acute-care facility with four community-based outpatient clinics. It provides care to 62,000 veterans living in and around Chicago and the six-county area in Northwestern Indiana.

The medical center had been purchasing its steam from the neighboring campus of the University of Illinois at Chicago and its electricity from ComEd. The cogeneration system has added a layer of redundancy to the medical center’s electricity supply, strengthening its reliability beyond the grid connection and emergency generators.

A Bit of History
Beginning in 1997, the US Department of Veterans Affairs began looking at how it could reduce utility bill expenses. It evaluated cogeneration in all 168 VA medical facilities, and identified 48 that held great potential for energy cost savings.

According to Ed Bradley, the VA’s acting director of the investment and enterprise development service in Washington DC, to date, cogeneration systems have been installed at three VA hospitals, Jesse Brown being the latest. Systems have already been installed at the North Chicago VA Medical Center and the James H. Quillen VA Medical Center in Johnson City, TN. Bradley says feasibility studies are progressing on nine more facilities, mainly in California, but also in Pennsylvania and other locations.

Bradley not only led the VA’s initial feasibility study, he was also the portfolio manager for the three cogeneration -projects.

ESG Given Lease
The VA is using “enhanced-use leasing” to take underutilized land and facilities and lease them to the public or private sector in order to enhance services to its veterans, explains Bradley. He says the VA obtained legislation in 1991 that created enhanced-use leasing, and has since used it to create transitional housing, single-room occupancy hotels, child-care centers, parking structures, and office buildings, in addition to the cogeneration centers.

Following a solicitation in 2002 for the design and construction of an energy center at Jesse Brown VAMC, the VA panel reviewing bids selected ESG, based on its proposal, and signed two agreements. First, it contracted out the design and construction of the energy center to ESG. Second, using its new “enhanced use leasing” tool, the VA leased to ESG an unoccupied, two-story, 200,000-square-foot concrete warehouse next to the medical center. Originally a dairy building built in 1920, it was transformed into the energy center where the turbine, steam generator, and auxiliary equipment are housed.

Street-level and aerial views of the facility, and a look at the uncluttered plumbing.

Full-Service Energy Center
The power-generation package is driven by a Solar Centaur model 40, 3.4-MW gas turbine. It supplies 100% of winter-peak and 90% of summer-peak power, according to ESG’s Luke Brockman. The Centaur 40 design has a heat rate of 12,240 Btu/kWe-hour and exhaust temperatures ranging from 600°F to 900°F, with an average of 819°F. A Solar-designed SoLoNOx emissions control system is also part of the package.

Russell Bruno was Solar’s district manager when the turbine was installed. He is now Solar’s commissioning manager in Texas. He describes the Centaur model as an older design that has been manufactured since 1969. Most of the time, the Solar Taurus is installed for cogeneration packages, but in this application, the Centaur fit the design and load better, he says. It is typically used for offshore power and on land from the arctic to the tropics, he says.

Darryl Joniak, the Solar field service representative for the project said the six-to-eight-week installation went smoothly. But Chicago’s summer heat, many times registering 100°F, reduces the turbine’s power production. So ESG chills the outside air 20 to 30 degrees when it is above 70°F before it enters the turbine, to control it to 60°F, he explains.

Both the six-month and one-year maintenance work on the turbine can be completed in one weekend, Joniak says, to avoid weekday utility-demand charges. Performance goes down when the compressor section gets dirty from the air being sucked in with fuel, he says, because clearances are extremely small and any amount of film on the blades reduces the amount of air flow and engine temperature control in back.

To maintain performance of the turbine, the interior of the engine/compressor section has to be cleaned regularly Joniak says. Once the engine is cooled, “they shoot soap and water in the air inlet ducts, let it sit, and rinse it out,” about a two-hour job, Joniak explains.

The combustion turbine’s waste heat is fed into a Deltak heat-recovery steam generator, which has a capacity of producing 52,000 pound/hour of steam with duct-firing. The temperatures of the waste heat coming out of the turbine are dictated by the electrical load, according to Brockman, and output of the steam generator depends on outside temperatures.

Duct Burners Boost Efficiency
During winter months, turbine waste heat is not adequate to produce the steam requirement for space heating, so two duct burners were installed directly in front of the steam generators. The duct burners boost the temperatures of the approximate 900°F waste heat coming out of the turbine to 1,500°F going into the steam generator, producing steam at 125 pounds of pressure—about 300°F. This steam produces all the requirements needed to maintain space heating in the hospital year-round, including the cold Chicago winter months, Brockman says. Two gas-fired boilers are available as backups for use when the turbine is down for maintenance, he explains.

Duane Wilson, Solar’s sales representative for the project, said the turbine is designed to have a thermal efficiency of 75%, assuming 15% oxygen at zero elevation. With duct burning in front of the steam generator, thermal efficiency can be boosted to as much as 99%, he says. “It allows a customer to load-follow and burn gas more efficiently. The additional steam is made more efficiently in the steam generator than in the package boiler,” Wilson adds.

The heating, ventilating, and air-conditioning system is a variable air volume system that requires both chilled water and steam simultaneously to maintain space temperature conditions. During the summer months, the system produces more than an adequate amount of the steam requirement, allowing the excess steam generated to be used in an 800-ton Trane absorption chiller that supplies half the chilled water supply needed in the medical center, according to Brockman. The remainder is produced by one or more of the three 710-ton electric chillers. The chilled water system is shut down around October 15 and outside air is used to mix with steam for temperature control until around April 15.

Chief engineer Hughes explains that the cogeneration system operates in parallel with ComEd and, when the load exceeds what the turbine produces, utility-generated power makes up the difference. He says ComEd has been very cooperative and the only problems that arose occurred during startup testing. The controls initially picked up variations in supply or voltage drops, and triggered automatic transfers to utility power. ESG quickly adjusted controls, Hughes says, and the problem disappeared.

Joniak attributes the problem to the medical center’s old high-voltage switchgear. “New stuff meeting up with old stuff does produce problems,” he comments.

Owner Trust Financed Project
ESG raised the $13 million funding for the design, construction, and installation of the project by creating an owner trust, which then sold bonds used for financing. In turn, the owner trust contracted with ESG to operate and maintain the energy center for 25 years. Under an option in the contract, the VA may continue with ESG after 10 years, or may identify a new O&M contractor.

The trust bills the VAMC for electricity and steam, pays the principal and interest on the bonds, and pays ESG as the operator of the energy center. Furthermore, it places contingency dollars into a maintenance reserve-fund to cover major repairs and enhancements that might be necessary over the next 25 years.

Dan Harsh, vice president in charge of finance and contracts at ESG, describes the owner trust as being similar to a limited liability company (LLC). Ownership of the energy center is invested in the trust to make it a “bankruptcy remote entity,” explains Harsh. Should ESG go bankrupt, the VA would replace ESG as the operator of the energy center with another contractor.

There are no distinct advantages of an owner trust over an LLC, Harsh observes. He says the owner trust was used as it was for the Johnson City and North Chicago energy centers—which ESG also built for the VA—at the suggestion of the VA in 1999.

Savings at Jesse Brown VAMC are estimated at $31 million over the next 25 years, but actual savings are not yet known, the VA’s Bradley says. “We will go back and run the numbers [in December 2005 or early in 2006],” he says. A consultant will be hired to look at the baseline utility usage contained in ComEd records and compare those numbers to the operating performance of the cogeneration system, he explains.

In the end, once the bonds are paid off, the VA will have the option to dissolve the owner trust and take ownership of the fully equipped energy center at the Jesse Brown VAMC. That’s a pretty good deal for the government and, ultimately, tax payers—not having to invest any up-front capital costs while still enjoying estimated energy savings of over $1 million a year.

California-based LYN CORUM is a technical writer specializing in energy topics.

DE - January/February 2006